I hear and agree all your tech opinions, but it bothering me the most is the price, that all the sigma lens (I could find) with or without OS on either mount are the same price (sigma 70-200 2.8 all has OS on different mount and same price), whereas tamron has more reasonable price difference on that example the guy just point out (17-50 2.8). That at least makes me feel better buying it. If sigma insist to have the same price through all mount with or without OS, they should at least throw in a better glass to the lens that doesn't have OS than the counterpart instead of that useless WEIGHT in the lens. Or it'll just seems that they're in favor of nikon and canon customers to me.